The present invention relates generally to heat exchanger assemblies, and more particularly to such heat exchanger assemblies employed as evaporator assemblies in ice making machines. The present invention also relates to a method of fabricating such heat exchanger or evaporator assemblies.
Various types of heat exchanger assemblies, including evaporator assemblies for ice making machines, frequently include a wall composed of a heat transmissive material and a plurality of sections of spaced-apart elongated fluid conduits, also composed of a heat transmissive material, disposed on one side of the wall for conveying a heat transfer fluid therethrough in order to transfer heat between the heat transfer fluid in the fluid conduits and the opposite side of the wall. The heat transfer efficiency of such heat exchanger assemblies is largely dependent upon the area of contact for conductive heat transfer between the fluid conduits and the heat transmissive wall. Such heat transfer efficiency is especially important in ice making machines with evaporator assemblies having a generally cylindrical evaporator tube and a helical fluid conduit positioned on the exterior side of the evaporator tube with axially adjacent turns of the helical fluid conduit being axially spaced apart from one another. In such ice making machines, the heat transfer efficiency of the evaporator assembly has a very significant bearing upon the quantity of ice that the ice making machine is capable of producing in a given time, as well as the cost of operating the ice making machine.
In the above-mentioned prior ice making machines, as well as in other heat exchanger devices, the adjacent turns or sections of the fluid conduits are spaced apart from one another and are typically of a cross-sectional shape having generally arcuate sides. Thus the area of contact between the fluid conduit and the heat transmissive wall is typically limited to a relatively small percentage of the outer surface areas of the heat transmissive wall and the fluid conduits, thus resulting in a relatively small heat transmissive conduction or contact area therebetween. Various attempts have been made to increase the area of contact, and thus the area of the heat conductive path, between the heat transmissive wall and the fluid conduits or conduit sections. Several examples of such attempts are disclosed in U.S. Pat. Nos. 1,841,762; 1,886,553; 1,987,707; 2,266,766; 2,578,917; 2,616,270; 3,120,869; 3,143,167; 3,196,624; 3,464,220; 3,972,821; and 4,185,369.
While such previous attempts have met with varying degrees of success, they have either not been fully effective in maximizing the area of contact, and thus the heat conductive path, between the fluid conduit and the heat transmissive wall, or they have done so only by resorting to inordinately complex structures that are difficult and relatively expensive to manufacture and install. Therefore, it is an object of the present invention to improve the area of contact, and thus the heat conductive path, between a fluid conduit or conduit sections and a heat transmissive wall in an evaporator assembly or other heat exchanger device.
A further object of the present invention is to provide such an improved heat exchanger or evaporator assembly that is relatively simple and inexpensive to manufacture and install, and that thus provides an optimized relationship between efficient heat transfer, simplicity, and economy.
In accordance with the present invention, an improved heat exchanger assembly has a wall composed of a heat transmissive material and a plurality of sections of spaced-apart elongated fluid conduits also composed of a heat transmissive material disposed on one side of the wall for conveying a heat transfer fluid therethrough. The assembly includes an elongated filler member extending longitudinally through the space between at least one adjacent pair of the spaced-apart elongated fluid conduits or conduit sections, with the elongated filler member also being composed of a heat transmissive material. The filler member can be disposed relatively close to the adjacent fluid conduits, but spaced slightly therefrom in order to form an elongated space or opening therebetween. A heat transmissive fusion material, such as silver solder for example, substantially fills the elongated space or opening and contacts the filler member, the wall, and fluid conduits in order to bond them to one another and to provide a heat transmissive path therebetween. Preferably, the heat transmissive fusion material is introduced into the assembly in a flowable state, with the flowable fusion material flowing into the elongated space or opening under the influence of capillary action.
In one optional embodiment of the invention, the elongated filler member can include a substantially solid outer surface with a plurality of longitudinally spaced-apart protrusions extending laterally outward from the outer surface. Such optional protrusions contact the adjacent fluid conduits when the filler member is installed in order to provide a plurality of spaces defining a plurality of openings between the filler member and the fluid conduits. In another embodiment of the invention, the filler member is fabricated from a plurality of interconnected heat transmissive wire members, therefore forming an elongated wire mesh structure with the wire members being spaced apart along portions thereof in order to form and define openings in or through the filler member. Preferably, the fluid conduits are composed of a copper-bearing tubing, the filler member is composed of a copper-bearing material, and the fusion material is composed of a silver solder or other such heat transmissive fusing agent.
In the preferred forms of both of the preferred embodiments described above, the filler member is fabricated with a generally three-sided lateral cross-sectional shape, with a first of the three sides of the filler member contacting the heat transmissive wall, and with the other sides being disposed adjacent the fluid conduits. In the optional embodiment described above wherein the filler member has a substantially solid outer surface with laterally outwardly-extending protrusions, such protrusions are disposed on the sides of the three-sided cross-sectional shape that are adjacent the fluid conduit sections. In the various arrangements described above, the above-mentioned opening or openings are defined by the space or spaces between the filler member and the adjacent fluid conduits and/or by the spaces between the above-mentioned heat transmissive wire members. Thus, the flowable fusion material is introduced into the openings and flows by capillary action to substantially fill the spaces or openings between the filler member and the fluid conduit sections, as well as contacting and bonding together the fluid conduit sections, the filler member, and the heat transmissive wall.
In the embodiment mentioned above wherein the filler member is composed of an elongated wire mesh structure, the openings in the wire mesh structure can be disposed throughout the filler member, thereby allowing the flowable fusion material to be introduced into the openings and flow therethrough by capillary action in order to substantially fill the voids in the wire mesh structure and to contact and bond together the fluid conduit sections, the filler member, and the heat transmissive wall. It should further be noted that in any of the embodiments of the present invention, the preferred heat exchanger assembly is substantially coated with the heat transmissive fusion material at least on the side of the heat transmissive wall wherein the fluid conduits and the filler member are disposed.
Additional objects, advantages and features of the present invention will become apparent from the following description and appended claims, taken in conjunction with the accompanying drawings.